1. Technical Field
The present invention relates to a photographing optical lens assembly. More particularly, the present invention relates to a compact photographing optical lens assembly applicable to electronic products.
2. Description of Related Art
In recent years, with the popularity of mobile products with camera functionalities, the demand for compact photographing lenses is increasing, and the sensor of a conventional photographing camera is none other than CCD (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor Sensor). Furthermore, as advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced and compact photographing lenses have gradually evolved toward higher megapixels, there is an increasing demand for compact photographing lenses featuring better image quality.
A conventional compact photographing lens assembly on a portable electronic product mainly adopts a three-element lens structure, as disclosed in U.S. Pat. No. 7,145,736, wherein a lens system thereof has a first lens element with positive refractive power, a second lens element with negative refractive power and a third lens element with positive refractive power arranged in order from an object-side to an image-side. However, due to the advancement of the manufacturing technology and the demand for compact camera units on various mobile products, the three-element lens structure cannot produce high quality images when the total optical track length decreases. Additionally, the three-element lens structure cannot satisfy the requirements of the higher-level camera modules.
Furthermore, another conventional compact photographing lens assembly provides a four-element lens structure, as disclosed in U.S. Pat. No. 7,365,920. The first lens element and the second lens element of the four-element lens structure are two glass lens elements with spherical surfaces which are attached to each other to form a doublet lens for the purpose of eliminating the chromatic aberration. However, this lens structure requires a longer total optical track length due to lower degrees of freedom in setting system parameters by allocating too many spherical lenses, and the manufacturing process for forming the glass doublet lenses can be difficult.
Therefore, a need exists in the art for providing a photographing lens assembly that features better image quality, maintains a moderate total track length, and is easy to manufacture.